Harold Hall
Workshop Processes
11
12
13
An Angle Plate
It will frequently be found that an angle plate will have advantages over using a vice when positioning a part for machining. Typical examples of this can be seen in Photograph's 11 and 12 where in the first the width of the part was machined parallel so that its thickness can be machined, as was seen in photograph 10 After thicknessing, this part was machined (photograph 12) with a fence being fitted on the left to ensure the part was accurately located.
Slitting Saw
One simple device that will only find occasional use but be invaluable on such occasions is a slitting saw. In addition to the saw itself, an arbor will be required and in this situation one with a shank to be held in the milling chuck will be the best solution, that in Photograph 13 being typical. Do when using a slitting saw ensure that you do not run it at too high a speed as there being very little metal to absorb the heat developed they easily over heat. This is particularly a problem with very thin saws.
Connecting Rod
Whilst in my original magazine article I included here the method of turning the barrel shaped con rod I have decided to present it as a separate item for viewers who may like to take note of its contents for another engine
Using the Milling Head
Using only the cross slide table.
The greatest limitation of milling in the lathe is the size of parts that can be accommodated and the engine's base at 315mm long is quite a large item. However, this is made of aluminium and was relatively easy to get the underneath sufficiently flat using a file, checking it against a surface plate. A high degree of accuracy is not required but sufficient to enable it to be clamped to the lathes cross slide without it being distorted. With that done I considered it possible to move the base on the cross slide so that the upper surfaces, seven in all, can be machined in stages.
Ideally, the four lands that support the cylinder assembly, should be machined at one setting to ensure that these sit accurately at the same level. With a traverse requirement of about 150 mm and this being within the travel of my cross slide I considered that there would be no problem. However, I had overlooked the effect of the large overhang of the casting at the rear and found that this would contact the workshop wall before the full area was machined.